This invention relates generally to a device for indicating whether an electrical receptacle is energized.
A common problem in household and industry arises when it is necessary to determine whether a particular wall switch or wall receptacle is part of a specific electrical circuit. One commonly used method in determining whether a particular electrical device, such as a wall receptacle, is part of a circuit involves the use of two people. One person is positioned near the receptacle with a voltmeter or "multimeter", or perhaps another electric device which is switched to its "on" position, while the other person is positioned adjacent a circuit breaker box. The person adjacent the breaker box then begins to switch breaker switches in the box one by one from an "on" to an "off" position until the person near the receptacle shouts out, or through use of a walkie-talkie radio, or the like, notifies the person near the breaker box that the breaker for the proper circuit has been found. This, of course, is determined by the person near the outlet recognizing when either the multimeter or the electrical device no longer receives power. As can be seen, this is a cumbersome, crude method of locating the circuit for a particular receptacle, but this method is commonly used.
For safety reasons, it is critical that before work can be done on a receptacle the circuit containing the receptacle is de-energized. That is why selection and de-energization of the correct circuit is so critical. Also, there may be times when it is desirable to de-energize a series of selected receptacles simultaneously, which further complicates locating the particular circuits for the receptacles, as one or more of the receptacles may share a common circuit.
In addition to isolating a circuit for a receptacle when the receptacle is to be replaced or repaired, another important reason to isolate the circuit arises when a particular electrical appliance is not working properly. In order to determine whether the appliance itself or the receptacle is defective, it becomes extremely useful to know whether the receptacle is actually energized. In many situations, this can only be determined by going through the above, or similar, process which requires the trial and error actuation of circuit breaker switches at the circuit breaker box. Locating particular receptacle circuits in an industrial environment can be complicated even further in that a variety of receptacles may be provided for the same work area, with individual or groups of such receptacles being on differing circuits.
It would also be helpful to provide means for quickly locating a receptacle in a residential or commercial environment. Location of receptacles may be complicated by the use of decorative, painted, or matching wallpaper-covered receptacle cover plates.
Devices have been patented which relate to locating electrical receptacles. U.S. Pat. No. 4,617,613, issued to Rice, discloses an illuminated mounting plate having spring-biased electric contacts for directly engaging with terminal screwheads in the side of a conventional receptacle. A resistor is connected to the spring-biased contacts, and a wire connects the resistor to a lamp, visible through a lamp housing provided on the cover plate. U.S. Pat. No. 4,774,641, also issued to Rice, discloses an illuminated electric outlet cover having bifurcated blades which are inserted into a conventional electric outlet for illuminating a lamp provided on the plate.
U.S. Pat. No. 3,265,888, issued to Adolphson, discloses a lighted receptacle having a neon lamp positioned in each outlet for illuminating the outlet in dark environments and also for indicating whether the receptacle is energized. U.S. Pat. No. 4,755,913, issued to Sleveland, discloses a light-emitting diode ("LED") for use in connection with a wall switchplate. A green LED indicates that the circuit is energized to carry current, and a red LED indicates that the switch is on.
U.S. Pat. No. 4,255,780, issued to Sakellaris, discloses an illumination assembly which can be used with switchplates and receptacle plates. Optical fiber means extend from an illumination source and are received in a hollow threaded shaft of an illumination display means, which is threadingly received in the conventional threaded hole provided in a metal mounting box. U.S. Pat. No. 2,385,620, issued to Fleckenstein, discloses an elongated receptacle cover having metal strips connectable with the outlet for energizing pilot lights. And, U.S. Pat. No. 2,612,597, issued to Sherrard, discloses an illuminated outlet device having a lamp provided in the outlet housing.
While the foregoing designs are known, there still exists a need for a practical, economical, and easy-to-install device for determining the circuit affiliation of a receptacle.